Narrative:

Aircraft X was stubbed because the inbound aircraft X was operating late. The flight was stubbed and our computer system electronically conditioned the call sign with a 'D'... Aircraft xd. This is the procedure per the flight manual. When the captain called for his clearance; ATC instructed him to change his call sign because using the delta suffix could cause confusion with a [different] airline flight. I manually changed the call sign to aircraft xp. This didn't go smoothly and took a couple of attempts to get the call sign changed in the ATC system. I suggest we don't use the letter D when subbing a flight. I can't really think of a worse letter to use when there is an airline with the same name. We're asking for confusion.

Google
 

Original NASA ASRS Text

Title: Air Carrier Dispatcher described a confusing situation that developed when his dispatching computer automatically assigned a 'D' suffix to the flight number of a stubbed flight taking the place of a late inbound flight with the same flight number. ATC rejected the 'D' suffix to avoid confusion with another carrier.

Narrative: Aircraft X was stubbed because the inbound Aircraft X was operating late. The flight was stubbed and our computer system electronically conditioned the call sign with a 'D'... Aircraft XD. this is the procedure per the Flight Manual. When the captain called for his clearance; ATC instructed him to change his call sign because using the delta suffix could cause confusion with a [different] airline flight. I manually changed the call sign to Aircraft XP. This didn't go smoothly and took a couple of attempts to get the call sign changed in the ATC system. I suggest we don't use the letter D when subbing a flight. I can't really think of a worse letter to use when there is an airline with the same name. We're asking for confusion.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.